Absorbent sanitary articles are used to collect various bodily fluids for hygiene purposes. For example, sanitary napkins are normally used by women during their menstrual periods to receive and contain blood discharges from the vagina. These articles are normally placed between the user's crotch and her undergarment. In addition to collecting menses, absorbent sanitary articles may also be used to protect the wearer's undergarment from other body fluid such as urine in the case of incontinence of the user.
Absorbent sanitary articles are generally built around a core containing an absorbent material (often a dried hydrogel) enclosed within a liquid pervious topsheet (skin-facing) and a backsheet (garment facing). In addition, other layers such as a secondary topsheet (STS) or lateral topsheet stripes (LTS) can also be built in the article to further improve its properties. The absorbent material within the core can theoretically trap relatively large amount of bodily fluids until saturation, however the user will normally change the article well before saturation for fear of premature failure of the article. One of the most common failures encountered is the leakage of previously absorbed fluid through the lateral sides of the article. Another common failure is the re-wetting of topsheet of the article by fluids previously absorbed within the core, which may happen when the wearer's movements subject the article to stress. In case of re-wet, the soiling of the longitudinal edges may also happen via the topsheet or STS if present.
It has been proposed in the past to use moisture indicators disposed along the side edges of the core to give early warning to the user of an imminent side leakage (WO91/19471). Whilst this system may improve the confidence of the user in the product, it however does not prevent the leakage itself and can be relatively costly and complicated to integrate in existing sanitary articles.
It has also been proposed, among other solutions, to increase the leakage resistance of the core by mixing fluid repellent fibers and fluid absorbent fibers in discrete area of the core, in particular its periphery (U.S. Pat. No. 5,817,079) or by “sealing” the core with an hydrophobic material (U.S. Pat. No. 4,015,604) or by incorporating a thermoplastic material between the absorbent core and the at least one fluid acquisition/distribution layer (EP1,579,831A1). As with the previous system, these methods suffer from being complicated and costly and have not been adopted by the industry.
Furthermore, improving the leakage resistance of a standard article by conventional, non-visible, means such as increasing the quantity of absorbent material in the core will not necessarily translate into better consumer benefits as the user will not change her pattern of product's usage and will continue to discard the article well before the item is saturated. Furthermore these may be costly.
There is therefore a need for a relatively cheap and simple system to provide sanitary articles with visibly improved resistance to leakage. The inventors have found that applying an ink in an area situated partially above the core and which also extends outwardly across at least a portion of the periphery of the core, can help preventing leakage along that portion of the periphery of the core and re-wetting. A simultaneous benefit is that this ink presents a visual clue to the user that the article has an improved resistance to leakage along that portion of the periphery of the core, e.g. the longitudinal edges. The ink may be relatively cheaply printed using conventional roll printing means on a layer of a standard article without the need to develop a new architecture of the article.